In this Wednesday, July 24, 2013 photo released by the U.S. Coast Guard, abatement efforts underway near Hercules 265 Rig where fire has caused collapse of the drill floor and derrick following an explosion Tuesday night. An out-of-control natural gas well burned Wednesday off Louisiana hours after it ignited following a blowout, though authorities said there was no sign of a slick on the surface of the water. (AP Photo/U.S. Coast Guard)

This photo released by the Bureau of Safety and Environmental Enforcement shows natural gas spewing from the Hercules 265 drilling rig in the Gulf of Mexico off the coast of Louisiana, Tuesday, July 23, 2013. No injuries were reported in the midmorning blowout and there was no fire as of Tuesday evening at the site, about 55 miles off the Louisiana coast in the Gulf of Mexico. (AP Photo/Bureau of Safety and Environmental Enforcement)

NEW ORLEANS (AP) — An out-of-control natural gas well burned Wednesday off Louisiana hours after it ignited following a blowout, though authorities said there was no sign of a slick on the surface of the water.

The Bureau of Safety and Environmental Enforcement says it saw no sheens near the well during flyovers Wednesday morning. The lack of sheen indicates the gas is burning off without releasing oil or other hydrocarbons — which are sometimes found in gas wells — into the water.

The fire broke out late Tuesday following a blowout in the morning, authorities said. Forty-four workers were evacuated from a drilling rig at the site, and no injuries were reported.

Officials stressed that the blowout wouldn't be nearly as damaging as the 2010 BP oil spill. That disaster included an explosion on the Deepwater Horizon drilling that killed 11 workers and the release of millions of gallons of oil into the Gulf of Mexico.

Natural gas generally poses much less of an environmental risk to the Gulf than crude oil, said several scientists contacted about Tuesday's blowout.

"Gas being discharged now would not necessarily affect the water system of the Gulf proper," said Donald Boesch, president of the University of Maryland's Center for Environmental Science and a member of the federal panel that investigated the BP oil spill. That's because it's likely most of the gas is venting directly into the atmosphere given the fire and shallow depth of the well, he said.

Also, by nature natural gas — mostly methane — is far more soluble than oil, meaning it more easily dissolves, dilutes and disperses than crude oil, Boesch said. And that means concentrations that are far less lethal to the marine environment, he said.

Federal authorities said in a news release that well owner Walter Oil & Gas was preparing to move equipment to the area in case it needs to drill a relief well. The owner of the blown rig, Hercules Offshore Inc., a contractor for well operator Walter Oil & Gas Corp., also said a relief well was among options being considered.

Two firefighting vessels had to be moved away to a safe distance from the fire, according to the federal news release. A third was being brought to the area.

The Coast Guard was keeping nautical traffic out of an area within 500 meters of the site. The Federal Aviation Administration restricted aircraft up to 2,000 feet above the area.

Tuesday's blowout occurred at a well where workers were using a portable drilling rig to complete a "sidetrack well." An offshore gas platform at the site was unmanned and wasn't currently producing gas.

Sidetrack wells are a means of re-entering the original well bore. Industry websites say such wells are sometimes drilled to remedy a problem with the existing well bore, or to tap into a different area of the oil or gas reserve. The companies involved declined to say why the sidetrack well was being drilled.

Boesch, the environmental science professor, said this type of well can be a problem because it's usually a "legacy" issue of older wells used and tapped out mostly by major oil companies that then move on and sell to smaller companies that have less capacity to deal with safety issues.

Boesch and others said it's likely that the fire and blowout can be stopped relatively easily, at least when compared to the BP disaster, especially since this is in shallow water.

Ted Bourgoyne, the former chair of Louisiana State University's petroleum engineering department, agreed that the blowout didn't pose a major environmental risk. He said that the smoke shouldn't be expected to create an air pollution problem for people onshore 55 miles away.

"A gas well's not going to result in any kind of major pollution — perhaps not even significant pollution if it's burning," said Bourgoyne, who now runs the consultancy Bourgoyne Enterprises Inc. "Whereas oil — we saw what happened with Macondo. That was a terrible event and the first time in 30 or 40 years they had one in the Gulf like that."

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Associated Press writers Ramit Plushnick-Masti in Houston and Seth Borenstein in Washington contributed to this story.

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